This proposal outlines psychophysical research techniques designed to study the changes in human color vision associated with primary open angle glaucoma. An improved understanding of the underlying functional changes in color vision caused by glaucoma will be addressed by measurement of fine discriminations along both chromatic and achromatic dimensions. Color perimetry using the procedures described in this proposal has been found to successfully differentiate glaucoma suspect and primary open angle glaucoma patients from normal age-matched controls. Long-term follow-up of these patients will determine the ability of the test to predict which ocular hypertensive eyes are most at risk for development glaucoma before topographic changes in the optic disc and standard visual field become apparent, and whether the test can used to monitor effectiveness of medical therapies employed in glaucoma. Finally, methods are incorporated which will determine the proportion of sensitivity loss due to normal aging on both standard white-on-white and color visual fields. Differentiation of age-related changes due to increased absorption of light by the ocular media and those due to retinal or neural changes will be possible. This will provide new information to assist in accurate diagnosis and treatment.